What is sending client info?

So, what does sending client info actually do? What happens specifically during that time? Is it the time that it downloads Lua files or what?

It’s sending basic player data, for example your skin settings.

Does it send info from the client to the server, from the server to the client, or both?

From the client to the server, you already received all of the information from the server as sending client info is the last stage of connecting.

Oh ok, thanks for the information.